Tourists hardly account for the majority of Demervallei's customers, even though the café is directly across the street from the Aarschot train station. Most of its customers are locals or from villages surrounding Aarschot (north-eastern Flemish Brabant). It certainly has had the time to build its clientele; Demervallei opened in 1925 and has kept its name through multiple ownership changes.
If upon entering Demervallei you can't figured out the draw, head to the WC. The water spout under which patrons wash their hands is a former beer tap, and the beer theme never ends. Ariaans, who bought Demervallei in 2005, has gradually grown the beer list that at last check numbered 510. Most are Belgian beers, though it's not uncommon to find a beer from the US, Norway or even China. There's a scattering of food on the menu, too, but it's the beer selection that keeps customers coming back.
Among the options are the hard-to-find Achel Trappists and even Westvleteren (though the latter will cost you nearly a tenner). You'll also find an original beer unavailable anywhere else in the world. Working with a local brewery, Ariaans developed both a brown and blonde version of a beer made specifically for his café.
Called "Deimerwaghter" after a statue in Aarschot of the same name, the beers have become a café favourite. Back on the Demervallei website, you can find a menu that links most beers to info about their make-up and taste —- in three languages.